Encode frame title and icon name before setting.

Encode frame title and icon name before setting.

* coding.h (ENCODE_UTF_8): Remove "Used by ..." comment.

* nsfns.m (ns_set_name_iconic): Remove.
(ns_set_name_internal): New function.
(Vicon_title_format): Extern declare.
(ns_set_name): Call ns_set_name_internal.
(x_explicitly_set_name): Remove call to ns_set_name_iconic.
(x_implicitly_set_name): Ditto.
(x_set_title): Remove commet about EXPLICIT.  Call ns_set_name_internal.
(ns_set_name_as_filename): Encode name with ENCODE_UTF_8 (Bug#7517).